GAY marriage opponents, and there are plenty of them, will be lining up to tell New Zealand MPs what they think of them when a select committee opens public hearings on the bill that legalises it.

They will have to be content with being angry and frustrated, because they aren’t going to overturn the 80-40 vote that put Louisa Wall’s bill through its first reading.

The majority was stronger than even the bill’s most optimistic supporters had hoped for.

They had their fingers crossed for 70 votes and didn’t know which way more than a third of parliament’s 121 MPs were going to go.

There was talk of the possibility that National’s mostly silent new intake would turn out to be conservatives, and might have the numbers to defeat the bill.

That didn’t happen. Most of the younger new Nats backed it, possibly influenced by the party’s youth wing which lobbied hard for the bill.

The select committee will have the power to change the bill, but it’s a simple piece of legislation and there isn’t much room to move.

Wall says a clause could be put in to make it explicit that churches won’t have to marry gay couples if they don’t want to, and that’s about it.

Wednesday’s hour-long debate was a quietly serious affair. Most speakers favoured the bill and explained why, opponents were at pains to point out they weren’t homophobic.

That was in stark contrast to the next day, when the alcohol purchase age was debated for more than two hours.

It quickly became clear that the government wasn’t going to get its way.

Few MPs were interested in the split age option – 18 in bars and 20 in supermarkets – which Prime Minister John Key and Justice Minister Judith Collins had been promoting and were confident would be adopted.

But these were conscience votes, and they didn’t have any control over their MPs who generally felt it was impractical, unfair and wouldn’t achieve much.

The real deal was whether the age should be kept at 18 or raised to 20, across the board.

It polarised parliament, with mostly older MPs arguing that lowering the age from 20 to 18 in 1999 had been an appalling mistake which had led to unprecedented binge drinking by young people.

“It’s the silliest thing we ever did,” said National’s Simon Bridges, who is 36 and looked as though he was on the wrong side.

But most of his Tauranga constituents are a lot older than he is, so he could get away with saying he wasn’t going to be influenced by the “pimply-faced” ignorance displayed by his party’s youth wing.

His caucus colleague Nikki Kaye, 32, who represents Auckland Central, waved statistics she said showed only 10 per cent of binge drinkers were teenagers and said there was no way she was going to penalise them for the wrongs of their elders.

Labour’s Lianne Dalziel, who started working on alcohol law reform when she was commerce minister in the previous government, doesn’t think the legislation Justice Minister Judith Collins has put forward – the age is just one part of it – will do anything to curb binge drinking.

“It isn’t about age, it’s about price and this is a gutless bill,” she told parliament.

Whether it’s gutless or not, the bill has taken four years to put together and it will be decades before another government has a shot at dealing with problems that aren’t going to go away.